1. Field of the Disclosure
The present disclosure relates to apparatus and methods for drilling a wellbore, lining the wellbore and cementing the wellbore during a single trip of a drill string downhole.
2. Background Art
Wellbores are drilled in earth formations using a drill string to produce hydrocarbons (oil and gas) from underground reservoirs. The wells are generally completed by placing a casing (also referred to herein as a “liner” or “tubular”) in the wellbore. The spacing between the liner and the wellbore inside, referred to as the “annulus,” is then filled with cement. The liner and the cement may be perforated to allow the hydrocarbons to flow from the reservoirs to the surface via a production string installed inside the liner. Some wells are drilled with drill strings that include an outer string that is made with the liner and an inner string that includes a drill bit (called a “pilot bit”), a bottomhole assembly and a steering device. The inner string is placed inside the outer string and securely attached therein at a suitable location. The pilot bit, bottomhole assembly and steering device extend past the liner to drill a deviated well. The pilot bit drills a pilot hole that is enlarged by a reamer bit attached to the bottom end of the liner. The liner is then anchored to the wellbore. The inner string is pulled out of the wellbore and the annulus between the wellbore and the liner is then cemented.
The disclosure herein provides a drill string and methods for using the same to drill a wellbore and cement the wellbore during a single trip.